Lamp socket adaptor



April 9, 1957 c. w. HERTEL 2,788,504

LAMP SOCKET ADAPTOR Filed Dec. 2, 1954 LAMP SOCKET ADAPTOR Charles W. Hertcl, Fcnton, Mo.

Application December 2, 1954, Serial No. 47 2,754

3 Claims. (Cl. 339-480) This invention relates to an adaptor for electric light sockets, whereby a standard threaded socket with a single spring contact in its base can be converted into a two-way socket.

Three-way threaded base light bulbs are presently in common use. Such bulbs are generally made in one of two types, the so-called mogul or oversize base and the standard base. This invention has particular application to the latter type.

Three-way light bulbs commonly contain two filaments of difierent sizes. The three way effect is achieved by selectively energizing first one "filament alone, then the other filament alone, and then both filaments together, although the particular order of energizing is not completely standardized.

The base of such a .light bulb has a contact on its bottom surface. The base diverges upwardly from its bottom to a threaded section or band of electrically conducting material insulated from the base contact. An upper contact is spaced above and outboard of the base contact, and is insulated both from the base contact and from the threaded section above it. The terms below and above are used herein in describing the lamp bulb, the socket and the adaptor to mean in a direction toward the base end of the bulb and away from the base end of the bulb respectively.

One of the .two filaments in the bulb is connected at one of its ends to the base contact and at the other of its ends to the threaded section. The other filament is connected at .one of its ends to the upper contact and at the other-of its ends to the threaded section.

In ,a three-way switch socket, a central spring contact bears against the base contact of the lamp while a ring contact, extending concentrically about the spring contact, .is positioned to engage the upper contact of the lamp. In such a three-way switch socket, the current is supplied to the ring contact alone, to the spring contact alone, and to both the spring and ring contacts together, in order selectively to energize the filaments as has been described.

While three-way lamp bulbs of the standard base type will fit in a standardsockegonly one of :the filaments can be energized, namely, the one which is attached to the base contact of the lamp, because a standard socket contains only a spring contact in its bottom.

One of the objects of this invention is to proyide a sate, simple, cheap, readily installed device by which .a standard lamp socket can be converted into a two-way socket without the use of tools, without changing the wiring, and without danger.

Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawing.

In accordance with this invention, generally stated, an adaptor .is provided which consists essentially of an outwardly expansible ring of electrically conducting material, and .a contact button spaced below the ring, an electrically connected thereto.

nited States Patent 2,788,594 Patented Apr. h, 1&5?

The ring and button are so positioned and arranged with respect to one another that when the adaptor is placed in a light socket, one side of the contact button engages the spring contact in the socket, and when a three-way lamp bulb is screwed into the socket, the bottom of the base extends through the ring to permit the upper contact of the lamp to engage the ring before the base contact engages the contact button. With continued tightening of the lamp bulb, the divergent base or the bulb spreads the .expansible ring sufficiently to permit the base contact of the lamp to engage the contact button or the adaptor, while at the same time the ring continues to engage the upper contact.

The adaptor can be so constructed that the upper contact of the lamp passes out et contact with the ring when the base contact engages the contact button of the adaptor, but that is not a preferred embodiment fora number of reasons which will be explained hereafter.

in the drawing:

Figure l is a view in side elevation partly in section, showing a lamp socket equipped with an adaptor constructed in accordance with one embodiment of this invention, with a lamp bulb screwed into upper lamp contact engaging position;

Figure 2 is a top plan view of an adaptor constructed in accordance with an illustrative embodiment of this invention;

Figure is a view in side elevation of the adaptor shown in Figure 2.;

Figure 4 is a bottom plan view of the device shown in Figure 2;. and

Figure 5 is an exploded view showing the componen elements .of the adaptor shown in Figure 2 before they are assembled.

Referring now .to the drawing for an illustrative embodimont .of this inyention, reference numeral 1 indicates an adaptor. As shown in Figure .1, the adaptor i is designed to fit in ,a standard light socket 2 in which a three-way, threaded standard base lamp bulb 3 is screwed.

The lamp bulb 3 includes a glass envelope 5 at the bottom of which is a base 7. The base 7 is made up of a threaded section 9 of electrically conducting material, a fiat bottom 11, and an upwardly divergent section 13 of insulating material.

A base contact 15 extends "from the center of the flat bottom 11. An upper contact 17 :is positioned below the threaded section ,9 and above and outboard of the base contact 15. One filament 19 is connected at one end to the upper contact 17 and at its other end, at '21, to the readed section .9. A second filament 23 is connected at one end to the base contact .15 and ,it its other end, at 25,10 the threaded section ,9.

The socket 2 includes an outer casing 30;, an insulating sleeve 32, an open ended cup 345 of electrically conducting material having a threaded section 3. 6, and a spring contact 38 at the center [of the bottom of .the socket. The spring contact 38 is electrically insulated from the cup 34. The .cup 34 is connected to one of the two Wires in a two-wire power system, while the spring contact 38 is connected to the other of the .two wires, generally through a switch not here shown.

The adaptor 1 shown in the drawing is made up of an outwardly enpansible ring 50 of electrically conductive material, such as brass, aluminum or the like, which in this embodiment takes the form of radially extending prongs 52. The ring 56 is, in the embodiment shown, electrically and mechanically connected with a .contact button 54, with which the prongs 52 are integral, as shown in Figures 1 and 5.. A washer 56 .of insulating material nds a und and b tween the utton 54 and the ing 0- 'The asher .56 ha an inside diameter larger than the normal diameter of the expansible ring 50 and an outside diameter such that the washer can be dropped into the socket 313 and yet serve substantially to center the contact button 54 in the socket. A washer 58, the outside diameter of which is smaller than that of the washer 56 and the inside diameter of which is approximately the same as or slightly smaller than the inside diameter of the washer 56, is made of electrically conducting material. The washer 58 overlies the washer 56 and is overlain by the prongs 52 of the ring 50, which prongs bear upon the upper surface of the washer 58.

In this embodiment, the prongs 52 are first bent in sharply toward the center of the contact button 54, then around but clear of the washers 56 and 58 and flat against the top surface of the washer 58, as best shown in Figure 1, and thus serve to hold the elements together.

The prongs 52 have sufiicient resilience so that they will spring back when displaced a short distance to the inner edge of the washers 56 and 58, which prevent any further spreading of the ring.

In operation, the assembled adaptor is simply dropped into the socket with the contact button down. The contact button, centered by the insulating washer 56 and insulated thereby from the cup 34, rests upon and makes electrical contact with the spring contact 38. When the lamp 3 is screwed into the socket, the upper lamp contact 17 will engage the ring 50 before the base contact 15 engages the contact button 54. Thus, if the lamp switch is in on position so that the cup 34 or the spring contact 38 as the case may be, is energized, current will flow through the threaded section 7, filament 19, contact 17, ring 50, contact button 54 and spring contact 38 to complete the circuit. If now the lamp bulb 3 is tightened in the socket, the diverging section 13 of the lamp base will act to spread the prongs 52 of the ring 50 to permit the base contact 15 to engage the upper side of the contact button 54 of the adaptor. In the embodiment shown, the upper contact 17 continues to engage the ring 50. Under these conditions, the circuit just described will remain completed While a second circuit through the cup 34, threaded section 7, filament 23, base contact 15, contact button 54 and spring contact 38 will also be completed.

Thus, by merely regulating the tightness with which the bulb is screwed into the socket, one can produce two degrees of illumination.

It can be seen that by making the ring 50 with a sharp inner edge, and spacing the contact button 54 well below that edge, an adaptor can be provided which will permit first one filament and then the other to be energized, since the upper contact 17 will have cleared the abrupt edge of the ring 50 before the base contact reaches the contact button 54. However, this is not a preferred form for several reasons. First, most persons prefer either to have the light on low or very high. The intermediate stage is seldom used. Secondly, the adaptor would have to be made more precisely, and third, because the size of the upper contact 17 is likely to vary with different lamps, the adaptor is not so likely to be fool proof.

It can even be seen that a three-way system is possible, if the contact button 54 is made resilient, as for example by so slotting it as to form inwardly radially extending flexible fingers. In that embodiment, the upper contact 17 would first meet the ring. With continued tightening, the base contact would meet the contact button 54 while the ring still engaged the upper contact 17. With still further tightening, the upper contact 17 would be forced below the ring 50 and out of engagement therewith, to leave only the base contact in engagement with the depressed resilient fingers of the contact button 54. This embodiment is also not preferrcd for the reasons assigned above to the embodiment in which the filaments were energized separately.

Numerous variations in the construction of the adaptor of this invention within the scope of the appended claims will occur to those skilled in the art in the light of the foregoing description. For example, it can be seen that the prongs 52, can be made fewer in number and of greater annular extent, to the point at which the ring takes the form of a split ring with sufficient resilience to permit the lamp bulb to be screwed down so that the base contact engages the top of the contact button.

The intermediate washer 58 may be omitted, particularly in those embodiments in which the prongs 52 are close together. The washers may be eliminated entirely, and the contact button 54 soldered or otherwise secured to or made a part of the spring contact 38. However, this latter arrangement lacks the advantage in simplicity of installation of the preferred embodiment.

A resilient washer of rubber or a spring washer may be sandwiched between the intermediate washer 58 and the washer 56, to provide additional tolerance for variations in the position and outward projection of the contact 17.

The contact 17, in fact, projects unnecessarily far on the usual bulb. If the projection is smoothed 01f (or if the bulbs are so manufactured), the resilient washer is unnecessary.

Thus, it can be seen that a simple, safe, effective adaptor is provided which is cheap to manufacture and easy to install.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. An adaptor for adapting a threaded electric lamp socket having a single spring contact in its bottom to use with a multifilament electric lamp bulb having an outwardly divergent base with a base contact at its bottom and an upper contact spaced above and outboard of said base contact and electrically insulated therefrom, said adaptor comprising an outwardly expansible, radially discontinuous ring of electrically conducting material, each discontinuity of the inside boundary of said ring being of lesser circumferential extent than that of the upper contact of the lamp bulb, the inside diameter of said ring being greater than the lowermost end of the base of the lamp bulb and normally less than the base at the upper contact of the lamp bulb; a contact button spaced from and below said ring and electrically connected to said ring, said button making electrical contact on its lower side with the spring contact of the lamp socket and being exposed on its upper side to the base contact of the lamp bulb, said button being spaced a vertical distance below the ring greater than the vertical distance of the base contact below the lowermost part of the upper contact, but less than the vertical distance of the base contact below the uppermost part of the upper contact; and a washer of electrically insulating material carrying said ring and button and extending radially beyond the said ring and button.

2. The adapter of claim 1 wherein the ring consists of radially outwardly extending prongs integral with said button, and the insulating washer is positioned between the prongs and the button, the prongs lying flat over the top surface of the washer.

3. The adaptor of claim 2 wherein a washer of electrically conducting material of an outside diameter less than that of the insulating washer overlies the upper surface of the insulating washer and the prongs of the ring overlie and bear upon the upper face of said electrically conducting washer.

References Cited in the file of this patent UNITED STATES PATENTS 1,187,723 George June 20, 1916 2,100,025 Douglas Nov. 23, 1937 2,265,360 Dessart Dec. 9, 1941 2,336,529 Cartun Dec. 14, 1943 

